Discharge device



Aug. 22, 1939. o. w. PIKE DISCHARGE DEVICE Filed Sept. 30, 1938 m I I r 1 I I n I n a ,a I I i i m w e f/d A m w O .s

Patented Aug. 22, 1939 PATENT OFFICE 2.110.095 nrscmmon nrvrca Otis W. Pike. Schenectady, N. Y.. assignmto General Electric Company, a corporation of New York Application September 30, 1938, Serial N0. 232,590

discharge devices to utilize envelope structures comprising an elongated glass or metal cylinder forming the main body of the envelope and transverse headers closing the ends of the envelope. To facilitate joining these parts and for certain 0 other reasons, it is desirable to form the headers of relatively thin metal having a thickness, say, on the order of 100 mils or less. This occasions no difliculty in connection with small tubes, but in large devices such as mercury pool tubes or 35 the like, the presence of a relatively large area of thin metal raises the danger of buckling due to pressure diiferences existing between the exterior and the interior of the envelope.

' It is an object of my present invention to provide means for effectively overcoming this danger without, at the same time, losing the advantages associated with a thin header construction. This is accomplished by applying to a selected portion of the header a reinforcing plate which is integrally joined to the header by means hereinafter to be described.

The features which I desire to protect herein are pointed out in the appended claims. The invention itself together with further objects and 3e advantages thereof may best be understood by reference to the following description taken in connection with the drawing in which Fig. 1 shows in longitudinal section a discharge device suitably embodying the invention; Fig. 2 is 5 an enlarged view showing a detail of the structure of Fig. 1; Fig. 3 comprises an alternative embodiment of the invention; and Fig. 4 is an enlarged detail of the fragmentary portion of Fig. 3. Referring particularly to Fig. 1, there is shown 49 a pool-typedischarge device adapted for relatively high power use. This comprises an elongated metal envelope comprising an outer cylinder ill and an inner cylinder H which is spaced from the outer cylinder so as to provide a water 45 jacket. The outer cylinder III may comprise a straight tubular section of sheet steel having a thickness, say, of 100 mils. The inner cylinder is preferably constituted of a chromium steel such as, for example, that sold as stainless steel".

5 The function of the chromium content is to prevent the infiltration of hydrogen from the water bath to the interior of the envelope.

Since stainless steel is a relatively expensive commodity, it is desired to use no more than 55 is absolutely necessary. To this end the cylinder ii is made of relatively thin material, say on the order of 100 mils or less. Its ends are provided with spun-out enlargements I4, I! which are adapted to interflt with the cylinder l8. Lineao welded joints are provided between the two y}.

4 Claims. (Cl. 250-275) inders so as to render the space between them water-tight. The ends of the envelope are respectively closed by dished metal members which comprise transverse header portions ll, 18 having peripheral flanges numbered I9 and 20.

Within the envelope there is provided appro-- priate electrode structure including an anode II, a mercury pool cathode 22 and a make-alive electrode 23, constituted of a semi-conductive material. The anode 2| and the electrode 23 are respectively supported from the upper and lower headers by means of glass-to-metal seals indicated at 25 and 28. The envelope as a whole may be exhausted and sealed off through a tubulation 21 provided in connection with the upper header.

Referring more specifically to the header structures, it is desirable that these structures be hermetically sealed to the main body of the envelope. To this end, it is expedient to join the flanges i9 and 20 to the inner surface of the cylinder H by line welding. This can be done effectively however, only if the thickness of the header material is approximately the same as that of the cylinder II, that is to say, of the thickness on the order of 100 mils or less. In connection with the traverse portion of the header, however, the use of a metal of this thinness raises the danger of distortion of the header due to pressure differences existing between the exterior and the interior of the envelope. Assuming that the latter is substantially completely evacuated, a relatively great total pressure may be exerted on the header surface if the header diameter is on the order 01' several inches or more.

Considerations of economy make it desirable that the header and its flange be of substantially uniform thickness so that the header can be spun or formed from a single piece of metal. It is, therefore, not expedient to make the central portion of the header greater in thickness than the flange. In order to overcome this difllculty, my invention provides in connection with the transverse header portion, a reenforcing plate which is integrally secured to the header surface so as to prevent any distortion thereof.

In connection with the upper header i! there is shown a plate which is applied to the outer surface of the header. This platemay have a thickness materially greater than that of the header, say on the order of V; inch, and may comprise any suitable structural material such as steel. In order that it may adhere firmly to the header, I provide a'brazed connection formed by the interposition of a suitable brazing material such as copper. The structure thus realized assures sufllcient rigidity to avoid distortion due to pressure diflerences and, at the same time, does not destroy the advantages associated with the use of a header element which is of uniform thickness throughout.

In connection with the lower header l8, there are provided reinforcing plates 33 and 34 respectively applied to the inner and outer surfaces of the header. These plates are applied by brazing as described in connection with the plate 30. The

' with openings 31 and 38 through which there extends a lead-in conductor 39 for the electrode 23. Externally of the envelope this conductor is insulated by means of a series of insulating beads 40. A heavy connection stud 4| is secured tothe lower reinforcing plate 35 for supplying current to the cathode 22.

In Fig. 3, a further application of my invention is illustrated in connection with a discharge device in which the main body of the envelope comprises an elongated glass cylinder 42. This cylinder encloses electrodes 43, 44 and 45 and is provided internally with a cooling coil 46 which extends longitudinally of the envelope. The upper end of the envelope is of reduced cross sectionand is closed by means of a glass-to-metal seal 41 from which the anode 43 is supported. The lower end of the envelope, however, is closed by a transverse header 49 which is, in many respects, similar to the headers described in connection with Figs. 1 and 2. In the present connection, however, it is desirable that the header 49 be constituted of a material which is capable of being sealed directly to glass such, for example, as the alloy of 18% cobalt, 28% nickel and 54% iron described in Burger and Hull Patent No. 2,071,196.

Since the alloy above referred to is' expensive, it is desirable to use only a thin section of it. This may be done without encountering danger of distortion of the header if its central region is reinforced in accordance with the principles of my invention. As in the cases previously described, this is done by the application of a steel backing plate 55, which is brazed or other wise secured to the header.

An opening provided in the backing plate accommodates the supporting structure for the electrode 44. As illustrated, this structure comprises a flanged sleeve 56 which is joined to the header as by welding thereto and an interfltting thimble 51 which is hermetically joined at its outer edge to the sleeve 56. A body of glass 59 supports the electrode 44 from the thimble 51 and provides a seal for a lead-in connection to the electrode. The current supply connection for the cathode comprises a heavy stud 60 which is secured to'the reenforcing plate 58.

The header 49 is provided with a peripheral flange 50 having a reversely bent portion 5| which is sealed directly to the end of the envelope cylinder so as to provide a glassto-metal joint at 53. This reversely bent portion, taken in connection with the main flange portion 50, serves to protect the glass-to-metal seal from excessive stress due to expansion of the header parts. It will be seen that the "goose-neck provided by the bent flange affords considerable flexibility in which expansive stresses can be taken up.

This flexibility is increased by the thinness of the header material, which may be on the order of mils or less.

While I have described my invention in connection with particular embodiments thereof, it will be understood that numerous modifications may be made by those skilled in the art without departing from the invention. I therefore aim in the appended claims to cover all such equivalent variations as fall within the true spirit and scope of the foregoing disclosure.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A discharge'device including electrode struc 2. A discharge device including electrode structure, a cylindrical metal envelope, a metal header closing one end of the envelope and having a flange which is continuously peripherally welded to the header, the said header having a thickness on the order of 100 mils or less so as to facilitate the welding operation, a reenforcing plate having a thickness greater than the header thickness, and a layer of brazing material rigidly joining the reenforcing plate to a surface of the header was to prevent deformation thereof by pressure differences existing between the interior and the exterior of the envelope.

3. A discharge device including electrode stmcture, an enclosing envelope comprising an elongated glass cylinder, a dished metal member forming a header and a peripheral flange continuous with the header, a sealed joint formed directly between the edge of the flange and the glass envelope, the m'etalmember having a thickness on the order of 100 mils or less whereby the said flange is sufiiciently flexible to prevent excessive stressing of said sealed joint by expansion of the header, and a reenforcing plate integrally joined to a surface of the header to prevent deformation thereof by pressure differences existing between the interior and theexterior of the envelope.

4. A discharge device including electrode structure, an enclosing envelope comprising an elongated glass cylinder, a dished member of thin metal forming a header and a flange continuous with the header, the said flange being provided with a reversely bent peripheral portion which is sealed at its edge directly to the glass envelope, and a reenforcing plate joined to the central portion of the header so as to increase its rigidity without decreasing the flexibility of the flange.

QTIS W. PIKE. 

